Zope/Plone 2.9 strange session behaviour?

This is what my server is running: (Zope 2.9.6-final, python 2.4.4, linux2)

I have a log-in form whe开发者_Go百科re user have to authenticate to the system. The Session expires after some time (say, 20 minutes).

If I am on a page (call it x) and my session expires (mean that when I click on a link, I will redirect to log in form) or I restart the server manually something strange happens: If I log-in again and click on some links (say all but not x) the page will be sended to me. If I request the x page (where I was before the session expire) the server redirect me on the log-in page (like I have no permission to access that page).

If I disable the cache on my browser, that problem seems to disappear.

Anyone knows what happening?

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I've seen problems where the 401 redirect ends up being cached by proxy caches. Plone 4.1 now sets appropriate cache headers to avoid this.